Alloy



UNHTEID STATES PATENT @FFEWEE.

WILLIAM E. SMITH, 0F CLEVELAND, OHIO, ASSIGNOR TO THE CLEVELAND BS8MANUFACTURING COMPANY, OF CLEVELAND, OHID, A CORPORATION OF OHM.

Patented Aug. 8, 1922.

ALLOY.

1,424,782. Specification of Letters Patent.

No Drawing. Application filed III-arch 23, 1918.

T0 all'whom it may concern Be it known that I, WILLIAM H. SMITH, acitizen of the United States, residing at Cleveland in the county'ofCuyahoga and State of Ohio, have invented a certain new and usefulImprovement in Alloys, of which the following is a full, clear, andexact description.

This invention relates to an alloy having many desirable inherentproperties, perhaps the most important of which is its resistance tocorrosion and surface flaking incident to repeated heating in thepresence of gases either oxidizing or reducing in character. Anotherimportant property of the alloy is its freedom from warping, crackingand breaking. And a still further advantageous property is the fact thatthe alloy has an exceedingl mits it to e subjected to high temperature.

A very important use for an alloy having the characterlstics describedis in the making of containers, sometimes known as saggars, which serveto hold articles which are to be in some manner subjected to a heattreatment.

Containers or boxes of this character have heretofore for the most partbeen made either from cast iron or steel. Such boxes in use arefrequently subjected to temperatures varying from 1650 Fahrenheit totemperatures in excess of 2000 Fahrenheit, and in the course of thistreatment are contacted by hot gases which may be of an oxidizing orreducing nature.

Experience has taught that boxes made of the material specified, aresubject to rapid deterioration due to the action of the hot gasescausing the formation of scale which is loosely adherent and drops off.

Another defect which develops from the use of cast iron or steel boxesis that they are exceedinly prone to warp, particularly on repeated use,andin an effort to overcome this deficiency, boxes having very thickwalls have been tried, and while perchance some improvement with regardto warping has been made, the difficulty has not been overcome, and theboxes so made are exceedingly heavy, making them difiicult to handle andexpensive to make. I

An alloy such as disclosed in thislcase,

when fabricated to form a heat treating box or container, is free fromthe objectionable flaking or warping characteristics of the cast highmelting point which per- Serial No. 224,113.

iron or steel boxes and permits a container to be made having thin wallsthereby reducing the weight of the container, and furthermore, theingredients are such that the cost of manufacture of the alloy is verymuch lower than the chromium-nickel-iron alloy to which reference hasbeen made.

The alloy of my invention comprises. a combination of iron, chromium,nickel, silicon and manganese as its principal elements, with carbonpresent in any quantity which. may result from the source of materialused. The alloy may contain 15 to 40 per cent of chromium, 1 to 3 percent of silicon, to 3 per cent of manganese, 1 to 10 per cent of mnickel, the balanceconsisting mainly of iron carbon. As before stated,the amount of carbon present in the final alloy is a matter of noconsequence and will vary in accordance with the quantity of carbonpresent in the initial raw materials, but usually it varies from 1% to 3per cent.

There may also appear in the final alloy,

traces of titanium for reasons which will later appear, and ifthe'source of ferrochrome employedin the making of the alloy is theproduct of the thermite process of producing ferro-chrome, aluminum willbe found in the final alloy.

An alloy which I have found to give very good results is of thefollowing composition:

18 per cent chromium.

2% per cent nickel.

' 2 per cent silicon.

1 per cent manganese.

Balance, iron and carbon.

The alloy is produced in the electric furg nace by melting commercialferro-chrome in its unrefined state, that is to say, ferro chrome whichis directly produced by the electric furnace process or the thermiteprocess. Ferro-chrome in this condition contains quite a high percentageof carbon, but I have discovered that the presence of this carbon is notat all deleterious to' the subloo 'se uent usage of the alloy.

tals of carbon which might otherwise form,

thereby assisting in causing the formation of carbides of iron andchromium in the ultimate. alloy.

Silicon is added to the alloy just before the furnace charge is poured.The silicon makes are added to the charge at about the same time as thesilicon is added, the purpose of the addition of titanium being to actas a.

scavenger to free the metal charge from occluded gases, particularlynitrogen. The quantity of titanium added is very small and is intendedto be only in such quantities as will flux out and not appear in thefinal alloy.

However, traces of titanium may be found in the final alloy, but thepresence of titanium is not disadvantageous.

The flux which is used is the usual and well known calcium flux, whichas before stated, takes up the titanium as well as part of the silicon.

In making the alloy it is only necessary to bring the temperature of thefurnace to a sufficient degree to insure a thorough meltihg andincorporation of the various elementsof the alloy. No refining of thealloy need be employed, for as before stated, the presence of carbon inany quantities is not disadvantageous.

The final alloy obtained is a metal which is very easily handled and canbe poured and cast in exactly the same manner as molten cast iron, andby methods usual and ordinary in cast iron foundry practice.

The alloy has a high tensile strength, and on fracture shows a finecompact gra n. The alloy is tough and resistant to breakage.

The melting point of the alloy is high, being in the neighborhood of2600 Fahrenheit.

A container cast from the alloy specified may be subject to oxidizing orreducing conditions in gas furnaces, and heated to such temperatures asare usually employed in such furnaces without in any substantial mannerdeteriorating. Apparently as soon as the boxes are heated, a protectivecovering of oxides of SlllCOIl, 1ron, chromium and possibly manganese isformed which protective covering is permanently adhesive to the surfaceof the box, and so protects against further deterioration. Furthermore,

the boxes or containers are non-warping even though the walls of thecontainers are. comparatively thin with respect to the thickness dients,iron, chromium and nickel, the iron '1 to 10 per cent of nickel, 1 to 2of walls of similar containers which have heretofore been usd.Containers of the alloy herein described. may be heated repeatedlywithout cracking, and are 'not at all fragile. They withstand the roughusage towhich they are subjected in handling while in use, which isanimportant element from the commercial standpoint.

In thissp'ecificationI have laid consider able stress upon 'ithe useofthe alloy in the making of heat treating boxes or saggars. However, thealloy has other uses than this, and may be employed very usefullywhereever a metallic surface or part is designed to withstand repeatedheatings under oxidizing or reducing conditions, where the propertiesheretofore described are necessary or desirable, such as furnace parts,crucibles, glass moulds, metal foundry moulds, zinc retorts, etc.

Having described my invention, I claim 1. An alloy containing asprincipal ingrepresent being not less than 50% nor greater than 85%, thenickel present being not less than 1% nor greater than 10%, togetherwith silicon from approximately 1 to 3%.

2. An alloy containing as principal ingredients, iron, chromium andnickel, the iron present being not less than 50% nor greater than 85%,the nickel present being not less than 1% nor greater than 10%, togetherwith silicon substantially 1 to 3% and manganese substantially l to 3%.

3. An alloy containing as ingredients sub stantially 15 to 40 per centof chromium, l to 10 per cent of nickel, 1 to 2 per cent of manganese,the balance being of iron, silicon and carbon.

4. An alloy containing as ingredients, substantially 15 to 40 per centof chromium,

per cent of manganese, 1 to 3 per cent of SillCOIl, the balance beingiron and carbon.

5.- An alloy containing as ingredients, substantially 18 per cent ofchromium, 2%,- per cent of nickel, 2 per cent of silicon, 1% per cent ofmanganese, with the balance iron and carbon. I

In testimony whereof, I hereunto afiix my signature.

- WILLIAM H. SMITH.

